Fix item icons to be more accurate

Project Amber is now the primary icon source!

src/handbook/data/README.md

@@ -5,3 +5,26 @@ Use Grasscutter's dumpers to generate the data to put here.
 - `avatars.json`
 - `commands.json`
 - `items.csv`
+
+# Item Icon Notes
+- Artifacts: `https://bbs.hoyolab.com/hoyowiki/picture/reliquary/(name)/(piece)_icon.png`
+  - Alternate source: `https://api.ambr.top/assets/UI/reliquary/UI_RelicIcon_(set)_(piece).png`
+  - `xxxx4` - `flower_of_life`
+  - `xxxx5` - `sands_of_eon`
+  - `xxxx3` - `circlet_of_logos`/`plume_of_death`
+    - Use `circlet_of_logos` with a complete set
+    - Use `plume_of_death` with part of a set.
+  - `xxxx2` - `plume_of_death`
+  - `xxxx1` - `goblet_of_eonothem`
+- Miscellaneous Items: `https://bbs.hoyolab.com/hoyowiki/picture/object/(name)_icon.png`
+  - Includes: materials, quest items, food, etc.
+  - Alternate source: `https://api.ambr.top/assets/UI/UI_ItemIcon_(id).png`
+- Avatars/Avatar Items: `https://bbs.hoyolab.com/hoyowiki/picture/character/(name)_icon.png`
+  - Avatar Items are between ranges `1001` and `1099`.
+- Weapons: `https://api.ambr.top/assets/UI/UI_EquipIcon_(type)_(name).png`
+- Furniture: `https://api.ambr.top/assets/UI/furniture/UI_Homeworld_(location)_(name).png`
+- Monsters: `https://api.ambr.top/assets/UI/monster/UI_MonsterIcon_(type)_(variant).png`
+
+# Credits
+- [`...List.json` files](https://raw.githubusercontent.com/Dituon/grasscutter-command-helper/main/data/en-US) - Grasscutter Command Helper
+- [Internal Asset API](https://ambr.top) - Project Amber